The present invention relates generally to motion picture or movie film devices and more particularly to a hand held motion picture viewing device which is adapted for viewing motion pictures from a film strip housed within a cartridge.
Hand held motion picture viewers adapted for viewing the images on successive frames of a film strip carried within a film cartridge are of course well known in the art. Typical viewers and cartridges of this type are shown for example in U.S. Pat. No. 3,306,697 to Nemeth and in U.S. Pat. Nos. 3,706,439 and 3,817,610 to Skinner et al. The viewers shown in these patents are of the manually operable type in which the film carried within the cartridge is advanced past a viewing aperture in the cartridge as a result of either a pawl engaging the perforations of the film or a sprocket wheel engaging the perforations of the film, each of which are coupled with and driven by a crank mechanism carried on the outside of the viewer manually operated by the user.
To avoid the use of a shutter mechanism the film must be moved to each succeeding frame fast enough so that film motion will not be detected by the person viewing the images. Typical prior art devices require either some type of film stopping mechanism or pawl and cam film engaging device for intermittent film motion.
The hand crank devices, whether with the cam and pawl drive, or in combination with the stop mechanism for intermittently moving the film, has a number of disadvantages. One such notable disadvantage is that these types of mechanisms are noisy when used. Additionally, the use of a manually operated drive mechanism has the disadvantage that film viewing speed is rarely constant. Operation of the hand crank can also be both tiresome and frustrating for certain individuals (particularly small children) who may have problems with eye and/or hand coordination.
The use of motorized drive mechanisms in hand held motion picture viewers for advancing the film carried within the cartridge is also well known in the art. One example of such a viewer is found in German Published Applications Nos. 26 04 770, 26 04 771 and 26 04 772. In this known viewer, a motor is used to drive an output shaft which, through a gear reduction transmission is coupled to a drive tooth which continuously rotates for engaging a film sprocket upon each revolution. While this and other known motorized movie viewers obviates the need for a hand crank thus avoiding the disadvantages connected therewith, such motorized viewers have other disadvantages, such as film slowdown when the battery reaches the end of its useful life and becomes weak, the inability to drive the film at a sufficiently low speed to minimize the size of the cartridge for maximum film viewing time, and inability to advance the film sufficiently fast to avoid detection of film motion.
It is accordingly one object of the present invention to provide a hand held motorized motion picture viewer which overcomes many of the disadvantages of the prior art.
A more specific object of the present invention is to provide a hand held motorized motion picture viewer which has a drive mechanism capable of intermittently advancing the film at speeds as low as 6 frames a second to maximize viewing time of the film carried within the cartridge.
A further specific object of the invention is to provide a hand held motorized movie viewer which includes a film driving claw for engaging and advancing the film in a cartridge which is driven in discrete arcuate steps.
Another object of the present invention is to provide a motion picture viewer which is battery operated but which avoids the undesirable effects of worn and weak batteries.
Yet a further object of the present invention is to provide a viewer with means for maximizing the viewing time available for viewing a film strip carried within a cartridge.
A still further object of the present invention is to provide a viewer and cartridge of the type in which the film is driven by a battery operated motor which is easy to use, minimizes eye discomfort, is relatively noiseless, and is relatively inexpensive to manufacture.
Other objects, features and advantages of the present invention will become more apparent from the detailed description of the invention in connection with the drawings to be described more fully hereinafter.